Air conditioner

ABSTRACT

An air conditioner (10) includes a refrigerant circuit (13) and refrigerant. The refrigerant circuit (13) has a compressor (1), a condenser (2), a pressure-regulating valve (3), and an evaporator (4). The refrigerant is R32. The pressure-regulating valve (3) includes a flow path (33) causing the refrigerant flowing from the condenser (2) to flow to the evaporator (4), a pressure reference chamber (S2) partitioned from the flow path (33) and filled with inert gas, and a valve portion (34) disposed in the flow path (33). The pressure-regulating valve (3) is configured to adjust a degree of opening of the valve portion (34) to adjust a flow rate of the refrigerant flowing through the flow path (33). The valve portion (34) is configured to increase the degree of opening when a pressure in the flow path (33) is higher than a pressure in the pressure reference chamber (S2), and reduce the degree of opening when the pressure in the flow path (33) is lower than the pressure in the pressure reference chamber (S2).

TECHNICAL FIELD

The present invention relates to air conditioners.

BACKGROUND ART

Air conditioners that reduce refrigerant consumption with the use of lowglobal warming potential (GWP) refrigerant are desired in considerationof global environment. Used as the refrigerant enabling such airconditioners that reduce refrigerant consumption with the use of low GWPrefrigerant is R32. R32 is refrigerant which has a small politropicexponent and whose temperature easily increases when discharged from acompressor. The use of R32 as refrigerant thus easily increases thetemperature of the refrigerant discharged from the compressor at highoutside temperature and at high condensation temperature. Since anincrease in the temperature of the refrigerant discharged from thecompressor may lead to a failure of the compressor, the temperature ofthe refrigerant discharged from the compressor is desired not to exceeda set temperature in order to prevent a failure of the compressor.

In a conventional air conditioner using R32 as refrigerant, thus, alinear expansion valve (LEV) is used to adjust the temperature of therefrigerant discharged from a compressor. Specifically, a microcomputercontrols the degree of opening of the LEV based on a signal from athermistor that has detected the temperature of the refrigerantdischarged from the compressor to adjust the temperature of therefrigerant discharged from the compressor not to exceed the settemperature.

For example, Japanese Patent Laying-Open No. 2016-109356 (PTL 1)discloses an air conditioner that uses R32 as refrigerant and includesan LEV.

CITATION LIST Patent Literature

PTL: 1: Japanese Patent Laying-Open No. 2016-109356

SUMMARY OF INVENTION Technical Problem

The air conditioner disclosed in the above literature has a longresponse time of the temperature of the refrigerant discharged from thecompressor with respect to the adjustment of the degree of opening ofthe LEV. Consequently, the adjustment of the degree of opening of theLEV may not keep up with an increase in the temperature of therefrigerant discharged from the compressor, allowing the temperature ofthe refrigerant discharged from the compressor to exceed the settemperature. A reduced amount of refrigerant may lead to a shorterresponse time of the temperature of the refrigerant discharged from thecompressor with respect to the adjustment of the degree of opening ofthe LEV. As a result, even when the degree of opening of the LEV isadjusted to allow the temperature of the refrigerant discharged from thecompressor to be equal to the set temperature, a phenomenon (hunting)occurs in which the temperature of the refrigerant discharged from thecompressor exceeds or falls below the set temperature.

The present invention has been made in view of the above problem and hasan object to provide an air conditioner that can suppress an increase inthe temperature of refrigerant discharged from a compressor and reducerefrigerant consumption with the use of low GWP refrigerant.

Solution to Problem

An air conditioner of the present invention includes a refrigerantcircuit and refrigerant. The refrigerant circuit has a compressor, acondenser, a pressure-regulating valve, and an evaporator. Therefrigerant flows through the refrigerant circuit in the order of thecompressor, the condenser, the pressure-regulating valve, and theevaporator. The refrigerant is R32. The pressure-regulating valveincludes a flow path causing the refrigerant flowing from the condenserto flow to the evaporator, a pressure reference chamber partitioned fromthe flow path and tilled with inert gas, and a valve portion disposed inthe flow path. The pressure-regulating valve is configured to adjust adegree of opening of the valve portion to adjust a flow rate of therefrigerant flowing through the flow path. The valve portion isconfigured to increase the degree of opening when a pressure in the flowpath is higher than a pressure in the pressure reference chamber andreduce the degree of opening when the pressure in the flow path is lowerthan the pressure in the pressure reference chamber.

Advantageous Effects of Invention

The air conditioner of the present invention sets the pressure in thepressure reference chamber to the pressure in the flow path where thetemperature of the refrigerant discharged from the compressor is a settemperature, and accordingly can increase the degree of opening of thevalve portion when the pressure in the flow path is higher than thepressure in the pressure reference chamber, thus suppressing thetemperature of the refrigerant discharged from the compressor exceedingthe set temperature. Also, the degree of opening of the valve portion isadjusted before the temperature of the refrigerant discharged from thecompressor exceeds the set temperature, thus suppressing the generationof hunting. R32 is low GWP refrigerant. Therefore, an air conditionerthat reduces refrigerant consumption with the use of low GWP refrigerantcan be achieved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 schematically shows the structure of a refrigerant circuit of anair conditioner in Embodiment 1 of the present invention.

FIG. 2 is a sectional view schematically showing the structure of apressure-regulating valve of the air conditioner in Embodiment 1 of thepresent invention.

FIG. 3 is a sectional view for illustrating an operation of a valveportion of the air conditioner in Embodiment 1 of the present invention.

FIG. 4 schematically shows the structure of a refrigerant circuit of anair conditioner in a comparative example.

FIG. 5 schematically shows the structure of a refrigerant circuit of anair conditioner in Embodiment 2 of the present invention.

FIG. 6 schematically shows the structure of a refrigerant circuit of anair conditioner in Embodiment 3 of the present invention.

FIG. 7 is a sectional view schematically showing the structure of apressure-regulating valve of a modification of the air conditioner inEmbodiment 3 of the present invention.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described below withreference to the drawings.

Embodiment 1

A configuration of an air conditioner 10 in Embodiment 1 of the presentinvention will be described with reference to FIG. 1. Air conditioner 10of the present embodiment is a device dedicated to cooling. That is tosay, air conditioner 10 of the present embodiment has a cooling functionand does not have a heating function.

Air conditioner 10 of the present embodiment mainly includes acompressor 1, a condenser 2, a pressure-regulating valve 3, anevaporator 4, a blower for condenser 5, a blower for evaporator 6, pipesPI1 to PI4, and refrigerant. Compressor 1, condenser 2,pressure-regulating valve 3, and blower for condenser 5 are accommodatedin an outdoor unit 11. Evaporator 4 and blower for evaporator 6 areaccommodated in an indoor unit 12.

Refrigerant circuit 13 has compressor 1, condenser 2,pressure-regulating valve 3, and evaporator 4. Compressor 1, condenser2, pressure-regulating valve 3, and evaporator 4 communicated with eachother through pipes PI1 to PI4 constitute refrigerant circuit 13.Specifically, compressor 1 and condenser 2 are connected to each otherby pipe PI1. Condenser 2 and pressure-regulating valve 3 are connectedto each other by pipe PI2. Pressure-regulating valve 3 and evaporator 4are connected to each other by pipe PI3. Evaporator 4 and compressor 1are connected to each other by pipe PI4.

Refrigerant circuit 13 is configured to allow refrigerant to circulatetherethrough in the order of compressor 1, pipe PI1, condenser 2, pipePI2, pressure-regulating valve 3, pipe PI3, evaporator 4, and pipe PI4.That is to say, refrigerant flows through refrigerant circuit 13 in theorder of compressor 1, condenser 2, pressure-regulating valve 3, andevaporator 4. Refrigerant is R32. The amount of the refrigerant flowingthrough refrigerant circuit 13 is preferably 300 g or more and 500 g orless.

Compressor 1 is configured to compress refrigerant. Compressor 1 is alsoconfigured to compress the sucked refrigerant and discharge thecompressed refrigerant. Compressor 1 is configured to have a variablecapacity. Compressor 1 of the present embodiment is configured tovariably control the number of rotations. Specifically, the drivefrequency of compressor 1 is changed based on an instruction from acontroller (not shown), so that the number of rotations of compressor 1is adjusted. This changes the capacity of compressor 1. The capacity ofcompressor 1 is an amount by which refrigerant is fed per unit time.That is to say, compressor 1 can perform a high-capacity operation and alow-capacity operation. In the high-capacity operation, an operation isperformed by setting the drive frequency of compressor 1 high toincrease the flow rate of refrigerant circulating through refrigerantcircuit 13. In the low-capacity operation, an operation is performed bysetting the drive frequency of compressor 1 low to reduce the flow rateof refrigerant circulating through refrigerant circuit 13.

Condenser 2 is configured to condense the refrigerant compressed bycompressor 1. Condenser 2 is an air-heat exchanger formed of a pipe anda fin. Pressure-regulating valve 3 is configured to decompress therefrigerant condensed by condenser 2. Pressure-regulating valve 3 hasthe function as an expansion valve. Pressure-regulating valve 3 is alsoa mechanical pressure control valve. Pressure-regulating valve 3 is alsoconfigured to adjust the flow rate of the refrigerant flowing throughpressure-regulating valve 3. The flow rate of the refrigerant flowingthrough pressure-regulating valve 3 is a flow rate per unit time.Evaporator 4 is configured to evaporate the refrigerant decompressed bypressure-regulating valve 3. Evaporator 4 is an air-heat exchangerformed of a pipe and a fin.

Blower for condenser 5 is configured to adjust a heat exchange amountbetween the outdoor air and refrigerant in condenser 2. Blower forcondenser 5 is formed of a fan 5 a and a motor 5 b. Motor 5 b may beconfigured to rotate fan 5 a such that the number of rotations of fan 5a is variable. Motor 5 b may also be configured to rotate fan 5 a suchthat the number of rotations of fan 5 a is constant. Blower forevaporator 6 is configured to adjust a heat exchange amount between theindoor air and refrigerant in evaporator 4. Blower for evaporator 6 isformed of a fan 6 a and a motor 6 b. Motor 6 b may be configured torotate fan 6 a such that the number of rotations of fan 6 a is variable.Motor 6 b may be configured to rotate fan 6 a such that the number ofrotations of fan 6 a is constant.

With reference to FIGS. 1 and 2, the configuration ofpressure-regulating valve 3 in the present embodiment will be describedin detail.

Pressure-regulating valve 3 includes a case 31, a diaphragm 32, a flowpath 33, a valve portion 34, a spring 35, and a partition member 36.Pressure-regulating valve 3 is configured to adjust the degree ofopening of valve portion 34 to adjust the flow rate of the refrigerantflowing through flow path 33.

Diaphragm 32 is attached to the inner side of case 31 to partition theinterior of case 31. Case 31 has a first chamber SI and a second chamberS2 partitioned by diaphragm 32.

First chamber S1 has flow path 33 which causes the refrigerant flowingfrom condenser 2 to flow to evaporator 4. Specifically, first chamber S1has a flow inlet portion 31 a and a flow outlet portion 31 b. Flow inletportion 31 a is connected to pipe PI2. Flow outlet portion 31 b isconnected to pipe PI3. First chamber S1 is configured to allow therefrigerant flowing through the refrigerant circuit to flow from pipePI2 through flow inlet portion 31 a into first chamber S1 and then flowthrough outlet portion 31 b to pipe PI3. That is to say, the refrigerantflowing through the refrigerant circuit flows into first chamber S1 fromflow inlet portion 31 a and flows out of flow outlet portion 31 b, asindicated by arrows A1 in FIG. 2. In the present embodiment, the pathfrom flow inlet portion 31 a to flow outlet portion 31 b forms flow path33 for refrigerant.

The pressure of first chamber S1 is a pressure of the refrigerant inflow path 33. Since the pressure of first chamber S1 is a pressure ofthe refrigerant flowing thereinto from condenser 2, it is a pressure ofhigh-pressure-side refrigerant flowing through refrigerant circuit 13.Pressure-regulating valve 3 is accordingly a high-pressurepressure-regulating valve.

Second chamber S2 forms a pressure reference chamber S2. Pressurereference chamber S2 is partitioned from flow path 33. Pressurereference chamber S2 is filled with inert gas. Pressure referencechamber S2 is hermetically sealed while being filled with inert gas. Thepressure in pressure reference chamber S2 is a pressure of the inertgas. The inert gas is, for example, nitrogen or helium. Nitrogen isadvantageous in low cost. Helium is advantageous in high level ofsafety. The pressure in pressure reference chamber S2 is, for example, 3MPa or more and 4 MPa or less.

Diaphragm 32 is configured to deform in the direction indicated by adouble-pointed arrow A2 in FIG. 2 due to a pressure difference betweenthe pressure of first chamber S1 and the pressure of second chamber S2,that is, a pressure difference between the pressure of the refrigerantin flow path 33 and the pressure of the inert gas in pressure referencechamber S2. Specifically, diaphragm 32 is configured to curve in aprojecting manner toward pressure reference chamber S2 when the pressureof the refrigerant in flow path 33 is higher than the pressure of theinert gas in pressure reference chamber S2. In contrast, diaphragm 32 isconfigured to be planar when the pressure of the refrigerant in flowpath 33 is equal to or lower than the pressure of the inert gas inpressure reference chamber S2. That is to say, in this case, diaphragm32 does not curve in a projecting manner toward pressure referencechamber S2.

Valve portion 34, spring 35, and partition member 36 are disposed infirst chamber S1. Partition member 36 is configured to partition firstchamber S1 into a first region on the flow inlet portion 31 a side and asecond region on the flow outlet portion 31 b side. That is to say,partition member 36 is disposed between flow inlet portion 31 a and flowoutlet portion 31 b in flow path 33 extending from flow inlet portion 31a to flow outlet portion 31 b.

Valve portion 34 has a valve body 34 a and a valve seat 34 b. Valveportion 34 is configured to adjust the degree of opening by the gapbetween valve body 34 a and valve seat 34 b. Valve body 34 a is formedin a shaft shape. One end (first end) of valve body 34 a is connected todiaphragm 32. The other end (second end) of valve body 34 a is connectedto spring 35. Valve body 34 a is configured to move in the directionindicated by a double-pointed arrow A3 in FIG. 2 due to the deformationof diaphragm 32. That is to say, valve body 34 a is configured to movein the axial direction of valve body 34 a due to the deformation ofdiaphragm 32. Valve body 34 a has a tapered shape with a cross-sectioncontinuously decreasing from the one end to the other end. Valve body 34a is formed in a truncated cone shape and is formed with a diametercontinuously decreasing in the axial direction toward valve seat 34 b.

Valve seat 34 b is provided in partition member 36. Valve seat 34 b isdisposed between flow inlet portion 31 a and flow outlet portion 31 b inflow path 33 extending from flow inlet portion 31 a to flow outletportion 31 b. Valve seat 34 b is provided around a valve hole 37 passingthrough valve seat 34 b. Valve body 34 a moves in the axial direction ofvalve body 34 a clue to the deformation of diaphragm 32 and accordinglyleaves valve seat 34 b, thereby opening valve hole 37. Specifically,when the pressure of the refrigerant in flow path 33 exceeds thepressure of the inert gas in pressure reference chamber S2, diaphragm 32curves in a projecting manner toward pressure reference chamber S2. Thiscauses valve body 34 a connected to diaphragm 32 to move toward pressurereference chamber S2 in the axial direction of valve body 34 a. Theother end of valve body 34 a accordingly leaves valve seat 34 b toexpose valve hole 37 from valve body 34 a, thereby opening valve hole37.

Valve seat 34 b is configured such that each of the surface (uppersurface) on the first region side of first chamber S1 and the surface(lower surface) on the second region side of first chamber S1 becomesdented. That is to say, valve seat 34 b has a dent on each of the firstregion side and the second region side of first chamber S1. In valveseat 34 b, the bottom of the dent on the first region side of firstchamber S1 and the bottom of the dent on the second region side of firstchamber S1 are communicated with each other. The bottom of the dent onthe first region side of first chamber S1 and the bottom of the dent onthe second region side of first chamber S1 which are communicated witheach other define valve hole 37.

Specifically, valve seat 34 b is formed such that each of the surface onthe first region side of first chamber S1 and the surface on the secondregion side of first chamber S1 is formed in a cone shape. Valve seat 34b is formed in a cone shape such that the surface on the first regionside of first chamber S1 has a diameter continuously decreasing towardthe second region of first chamber S1. The surface of valve seat 34 b onthe first region side of first chamber S1 is formed in a cone shape tohave a diameter continuously decreasing toward second region of firstchamber S1.

Valve portion 34 is configured to increase the degree of opening whenthe pressure in flow path 33 is higher than the pressure in pressurereference chamber S1. That is to say, valve portion 34 is configured asfollows. When the pressure in flow path 33 is higher than the pressurein pressure reference chamber S2, valve body 34 a moves toward diaphragm32 in the axial direction of valve body 34 a to increase the gap betweenvalve body 34 a and valve seat 34 b, thereby increasing the degree ofopening. Valve portion 34 is also configured to reduce the degree ofopening when the pressure in flow path 35 is lower than the pressure inpressure reference chamber S2. That is to say, valve portion 34 isconfigured as follows. When the pressure in flow path 35 is lower thanthe pressure in pressure reference chamber S2, valve body 34 a movestoward spring 35 in the axial direction of valve body 34 a to reduce thegap between valve body 34 a and valve seat 34 b, thereby reducing thedegree of opening.

Valve portion 34 is configured to continuously change the size of thegap between valve body 34 a and valve seat 34 b by valve body 34 amoving in the axial direction of valve body 34 a due to the deformationof diaphragm 32. That is to say, valve portion 34 is configured toincrease or reduce the degree of opening of valve portion 34 inproportional to the amount of movement in the axial direction of valvebody 34 a.

Spring 35 is connected to the other end of valve body 34 a and thebottom of case 31. Spring 35 is configured to bias valve body 34 atoward the bottom of case 31 by elastic force.

A small hole 38 is provided in partition member 36. Small hole 38 isprovided to pass through partition member 36. Small hole 38 defines apart of flow path 33. Since small hole 38 is not closed by valve body 34a and is open constantly, refrigerant can constantly flow through smallhole 38 front the first region to the second region in first chamber S1.In the present embodiment, small hole 38 has the function as acapillary. That is to say, the refrigerant is decompressed by flowingthrough small hole 38.

A flow of refrigerant in the refrigerant circuit of air conditioner 10of the present embodiment will now be described.

With reference to FIG. 1, the refrigerant that has flowed intocompressor 1 is compressed by compressor 1 to turn intohigh-temperature, high-pressure gas refrigerant. The high-temperature,high-pressure gas refrigerant discharged from compressor 1 flows throughpipe PI1 into condenser 2. The refrigerant that has flowed intocondenser 2 is subjected to heat exchange with the air in condenser 2.Specifically, in condenser 2, the refrigerant is condensed by heatdissipation to the air, and the air is heated by the refrigerant.High-pressure liquid refrigerant condensed by condenser 2 flows throughpipe PI2 into pressure-regulating valve 3.

The refrigerant that has flowed into pressure-regulating valve 3 isdecompressed by pressure-regulating valve 3 to turn into low-pressuregas-liquid two-phase refrigerant. The refrigerant decompressed bypressure-regulating valve 3 flows through pipe PI3 into evaporator 4.The refrigerant that has flowed into evaporator 4 is subjected to heatexchange with the air in evaporator 4. Specifically, in evaporator 4,the air is cooled by the refrigerant, and the refrigerant turns intolow-pressure gas refrigerant. The refrigerant decompressed by evaporator4 to turn into low-pressure gas flows through pipe PI4 into compressor1. The refrigerant flowing into compressor 1 is compressed andpressurized again and subsequently discharged from compressor 1.

With reference to FIGS. 2 and 3, the operation of pressure-regulatingvalve 3 in the present embodiment will now be described in detail.

When the pressure of the refrigerant in flow path 33 is equal to orlower than the pressure of the inert gas in pressure reference chamberS2, diaphragm 32 is maintained in a planar manner, so that valve body 34a is in contact with valve seat 34 b. This maintains the state in whichvalve hole 37 is closed by valve body 34 a. Valve portion 34 is closedin this state.

When the pressure of the refrigerant in flow path 33 is higher than thepressure of the inert gas in pressure reference chamber S2, diaphragm 32deforms in a projecting manner toward pressure reference chamber S2. Thedeformation of diaphragm 32 causes valve body 34 a to move towardpressure reference chamber S2 in the axial direction of valve body 34 a.Consequently, valve body 34 a leaves valve seat 34 b. In this state,valve portion 34 is opened. Further, when valve body 34 a moves towardpressure reference chamber S2 in the axial direction of valve body 34 adue to the deformation of diaphragm 32, the gap between valve body 34 aand valve seat 34 b increases. That is to say, the degree of opening ofvalve portion 34 increases. This increases the amount of refrigerantflowing through pressure-regulating valve 3, thus increasing the amountof refrigerant flowing into evaporator 4. The degree of superheat (SH)accordingly decreases. As a result, an increase in the temperature ofthe refrigerant discharged from compressor 1 can be suppressed.

The amount of movement in the axial direction of valve body 34 a can beadjusted by the pressure of the refrigerant in flow path 33, thepressure of the inert gas in pressure reference chamber S2, and thebiasing force of spring 35 connected to valve body 34 a. The degree ofopening of valve portion 34 can be adjusted by the gap between valvebody 34 a and valve seat 34 b. The amount of the refrigerant flowingthrough pressure-regulating valve 3 can thus be adjusted by adjustingthe amount of movement in the axial direction of valve body 34 a and thedegree of opening of valve portion 34.

The function and effect of the present embodiment will now be describedin comparison with those of a comparative example. The same componentsas those of Embodiment 1 will be denoted by the same reference signs,and description thereof will not be repeated, unless otherwise noted.

With reference to FIG. 4, air conditioner 10 of the comparative examplediffers from air conditioner 10 of the present embodiment in that itincludes a linear expansion valve (LEV) 30, a thermistor 7, and amicrocomputer 8. In air conditioner 10 of the comparative example,microcomputer 8 controls the degree of opening of LEV 30 based on asignal from thermistor 7 that has detected the temperature of therefrigerant discharged from compressor 1, so that the temperature of therefrigerant discharged from compressor 1 is adjusted not to exceed a settemperature (a temperature set to prevent a failure of compressor 1).

In air conditioner 10 of the present embodiment, refrigerant is R32. R32is refrigerant which has a small politropic exponent and whosetemperature easily increases when discharged from compressor 1. Thus,when R32 is used as refrigerant, the temperature of the refrigerantdischarged from compressor 1 increases easily at high outside air (highoutside air temperature) and at high condensation temperature.

Air conditioner 10 of the present embodiment sets the pressure inpressure reference chamber S2 to the pressure in flow path 33 where thetemperature of the refrigerant discharged from compressor 1 is the settemperature (the temperature set to prevent a failure of compressor 1),thereby increasing the degree of opening of valve portion 34 when thepressure in flow path 33 is higher than the pressure in pressurereference chamber S2. This can suppress the temperature of therefrigerant discharged from compressor 1 exceeding the set temperature.The amount of the refrigerant flowing into evaporator 4 can also beincreased by increasing the amount of the refrigerant flowing throughpressure-regulating valve 3, thus reducing the degree of superheat. Anincrease in the temperature of the refrigerant discharged fromcompressor 1 can thus be suppressed. Also, the generation of hunting canbe suppressed by adjusting the degree of opening of valve portion 34before the temperature of the refrigerant discharged from compressor 1exceeds the set temperature. R32 is low GWP refrigerant. Consequently,air conditioner 10 that reduces refrigerant consumption with the use oflow GWP refrigerant can be achieved.

Air conditioner 10 of the comparative example needs LEV 30, thermistor7, and microcomputer 8 to adjust the temperature of the refrigerantdischarged from compressor 1, leading to a complex configuration of airconditioner 10. Also, the cost of manufacturing air conditioner 10 isincreased. Contrastingly, in air conditioner 10 of the presentembodiment, pressure-regulating valve 3 can adjust the temperature ofthe refrigerant discharged from compressor 1, leading to a simpleconfiguration of air conditioner 10. Also, the cost of manufacturing airconditioner 10 is reduced.

In air conditioner 10 of the present embodiment, pressure-regulatingvalve 3 can adjust the flow rate of the refrigerant flowing through flowpath 33 by adjusting the degree of opening of valve portion 34. Thus,the generation of hunting can be suppressed more than in the case wherevalve portion 34 is merely opened/closed (ON/OFF). Also, thecontrollability of the flow rate of refrigerant can be improved.

In air conditioner 10 of the present embodiment, the amount ofrefrigerant flowing through refrigerant circuit 13 is 300 g or more and500 g or less. According to the documents provided by the Ministry ofEconomy, Trade and Industry (documents related to a method of estimatingemissions outside notification, 2003), the average refrigerantchlorofluorocarbon (CFC) charge amount of a room air conditioner is 800g. Air conditioner 10 of the present embodiment can thus reduce theamount of refrigerant to about a half of 800 g that is the averagerefrigerant CFC charge amount of a room air conditioner. If the amountof refrigerant is 400 g±100 g, where 400 g is a half of the averagerefrigerant CFC charge amount of a room air conditioner, the refrigerantconsumption can be reduced while maintaining the cooling capacity.

In air conditioner 10 of the comparative example, a reduced amount ofrefrigerant results in a shorter response time of the temperature of therefrigerant discharged from compressor 1 with respect to the adjustmentof the degree of opening of LEV 30, so hunting may occur at the settemperature. Contrastingly, air conditioner 10 of the present embodimentincreases the degree of opening of valve portion 34 with reference tothe pressure in pressure reference chamber S2, thereby suppressing thegeneration of hunting with respect to the set temperature even when theamount of refrigerant decreases. Controllability can thus be improved.

In air conditioner 10 of the present embodiment, compressor 1 canvariably control the number of rotations. Power consumption can thus bereduced by variably controlling the number of rotations of compressor 1.Also, even when the temperature of the refrigerant discharged fromcompressor 1 increases due to an increase in the number of rotations ofcompressor 1, an increase in the temperature of the refrigerantdischarged from compressor 1 can be suppressed by increasing the degreeof opening of valve portion 34 with reference to the pressure inpressure reference chamber S2.

Embodiment 2

The same components as those of Embodiment 1 will be denoted by the samereference signs in Embodiment 2, and description thereof will not berepeated, unless otherwise noted.

With reference to FIG. 5, air conditioner 10 of Embodiment 2 of thepresent invention differs from air conditioner 10 of Embodiment 1 in theconfiguration of pressure-regulating valve 3.

In air conditioner 10 of the present embodiment, pressure-regulatingvalve 3 includes a capillary 39. Capillary 39 is connected to case 31 ofpressure-regulating valve 3 and evaporator 4. The configuration in case31 of pressure-regulating valve 3 is identical to the configuration ofEmbodiment 1. Capillary 39 is disposed between valve portion 34 andevaporator 4 in refrigerant circuit 13. Capillary 39 can thus decompressthe refrigerant.

The present embodiment can adjust the decompression of refrigerant bycapillary 39. This leads to easier adjustment of the decompression ofthe refrigerant.

Embodiment 3

The same components as those of Embodiment 1 will be denoted by the samereference signs in Embodiment 3, and description thereof will not berepeated, unless otherwise noted.

With reference to FIG. 6, air conditioner 10 of Embodiment 3 of thepresent invention differs from air conditioner 10 of Embodiment 1 in theconfiguration of pressure-regulating valve 3.

In air conditioner 10 of the present embodiment, pressure-regulatingvalve 3 includes capillary 39. Capillary 39 is connected in parallelwith case 31 of pressure-regulating valve 3 in refrigerant circuit 13.The configuration in case 31 of pressure-regulating valve 3 is identicalto the configuration of Embodiment 1. Capillary 39 is disposed inparallel with valve portion 34 in refrigerant circuit 13. Capillary 39can thus decompress the refrigerant.

The present embodiment can accordingly adjust the decompression ofrefrigerant by capillary 39. The adjustment of the decompression ofrefrigerant can thus be simplified.

With reference to FIG. 7, a modification of air conditioner 10 ofEmbodiment 3 will now be described. This modification differs fromEmbodiment 1 in that small hole 38 is not provided. In thismodification, capillary 39 is disposed in parallel with valve portion 34in refrigerant circuit 13, and accordingly, capillary 39 can causerefrigerant to constantly flow through refrigerant circuit 13 even whensmall hole 38 of Embodiment 1 is not provided.

Capillary 39 can adjust the decompression of refrigerant more easilythan small hole 38 of Embodiment 1. In the modification of airconditioner 10 of the present embodiment, thus, capillary 39 can adjustthe decompression of refrigerant easily.

It is to be understood that the embodiments disclosed herein have beenpresented for the purpose of illustration and non-restrictive in everyrespect. It is therefore intended that the scope of the presentinvention is defined by claims, not only by the embodiments describedabove, and encompasses all modifications and variations equivalent inmeaning and scope to the claims.

REFERENCE SIGNS LIST

1 compressor, 2 condenser, 3 pressure-regulating valve, 4 evaporator, 5blower for condenser, 6 blower for evaporator, 7 thermistor, 8microcomputer, 9 capillary, 10 air conditioner, 11 outdoor unit, 12indoor unit, 13 refrigerant circuit, 31 case, 31 a flow inlet portion,31 b flow outlet portion, 32 diaphragm, 33 flow path, 34 a valve body,34 b valve seat, 35 spring, 36 partition member, 37 valve hole, 38 smallhole, 39 capillary, S1 first chamber, S2 second chamber (pressurereference chamber).

1-5. (canceled)
 6. An air conditioner comprising: a refrigerant circuitcomprising a compressor, a condenser, a pressure-regulating valve, andan evaporator; and refrigerant flowing through the refrigerant circuitin an order of the compressor, the condenser, the pressure-regulatingvalve, and the evaporator, wherein the refrigerant is R32, thepressure-regulating valve comprises a case, a diaphragm attached to aninner side of the case to partition an interior of the case, a flow pathprovided by partitioning the interior of the case by the diaphragm, theflow path causing the refrigerant flowing from the condenser to flow tothe evaporator, a pressure reference chamber partitioned from the flowpath by the diaphragm and filled with inert gas, a valve portiondisposed in the flow path, and a partition member disposed in the flowpath, the pressure-regulating valve is configured to adjust a degree ofopening of the valve portion to adjust a flow rate of the refrigerantflowing through the flow path, and the valve portion is configured toincrease the degree of opening when a pressure in the flow path ishigher than a pressure in the pressure reference chamber, and reduce thedegree of opening when the pressure in the flow path is lower than thepressure in the pressure reference chamber, the valve portion comprisesa valve body connected to the diaphragm, and a valve seat provided inthe partition member, and the pressure-regulating valve is configured tocause the refrigerant to flow into the pressure-regulating valve alsowhen the valve body is in contact with the valve seat, wherein thepressure-regulating valve comprises a capillary, and the capillary isdisposed between the valve portion and the evaporator in the refrigerantcircuit.
 7. The air conditioner according to claim 6, wherein an amountof the refrigerant flowing through the refrigerant circuit is 300 g ormore and 500 g or less.
 8. The air conditioner according to claim 6,wherein the compressor is configured to variably control a number ofrotations.